Like many of his middle-class neighbors in Mumbai, Bhakti Klein gets his water delivered to his home each week in a plastic bottle by the local grocery store. For 20 liters (just over five gallons), he pays 90 rupee, or $1.35 — nearly a third of the average Indian's daily income of $4.41. "We don't have a 24-hour water supply in my neighborhood yet, let alone potable water," says Klein, who is originally from the United States. "The entire water supply system would have to be improved before I would drink tap water."

India is now the world's third largest market for bottled water. According to the research firm Canadean, the amount India spent each year on bottled water nearly tripled from 2010 to 2015, growing from $6.275 billion to $16.7 billion. That represents 6 percent of the world's current bottled water consumption, a figure that Canadean expects to grow to 10 percent by 2020.

As massive as those figures sound, they pale in comparison to China's. From 2010-2015, according to research firm Euromonitor, China's annual consumption of bottled water rose from 19 billion liters to 37 billion. By 2013, China had overtaken the U.S. as the world's biggest market for bottled water by volume; in 2015, Chinese consumers spent more than $26.5 billion on this basic Earthly resource, and there is no sign of a slowing. Canadean predicts that China and India will consume about 45 billion liters more bottles of water in 2020 than they did in 2015.

Even though China and India do engage in some plastic recycling, we certainly don't need more plastic in the world; more important, those who need bottled water most cannot afford it even in those two countries. Consider this, from a report by WaterAid: While the water bill in developed countries such as the U.S. can represent as little as 0.1 percent of a minimum wage earner's income, for the poorest of the poor in a country like Papua New Guinea, that figure is close to 54 percent. In Kibera, a neighborhood in Nairobi dubbed Africa's largest slum, most people live on less than a dollar a day. Yet the average price for a liter of drinkable water is $0.75.

Much of this waste and its costs — environmentally, medically, and financially — is unnecessary. In various spots of the globe, determined water scientists have been devising simple, low-tech methods of creating clean water supplies, at both the neighborhood and household levels, at extremely moderate costs. What would it take to get more communities to use them?

The rise of bottled water

The phenomenal growth of the bottled water business — at least in developing countries — is largely due to a maddeningly fixable cause: problems with the local water supply.

In China, for example, the Ministry of Land and Resources noted in a 2015 report that 60 percent of 5,000 monitoring sites had groundwater that was polluted. Across the globe, the World Health Organization reports,1.8 billion people use a drinking water source contaminated with feces. The consequences of drinking contaminated water are profound. It can transmit diseases such as dysentery, cholera, typhoid, and schistosomiasis, also known as bilharzia, which can lead to liver damage or kidney failure and affects almost 240 million people worldwide. The World Heath Organization estimates that 500,000 people die every year from diarrhea caused by drinking contaminated water.

Now compare those sad numbers to this one: According to the United Nations Millennium Project's Task Force on Water and Sanitation, a few basic improvements in drinking-water quality, such as the use of household disinfectants, would reduce diarrhea episodes by a stunning 45 percent.

Chlorine: simple but not enough?

In Bilwi, a small village in Nicaragua, Maria Tucker and her family bought a ceramic filter for $48.00. The filters are designed to last 3 years. | (WaterAid/Courtesy Craftsmanship)

Chlorine, liquid bleach, or Aquatabs have long remained some of the most effective ways to disinfect water and kill germs. Not surprisingly, 98 percent of U.S. water treatment facilities use some form of chlorine. Organizations such as Dispensers for Safe Water provide chlorine-dosing stations at water collection points in Kenya, Uganda, and other countries.

Aquatabs claims to be the "world's number one water purification tablets," and are used by over 13 million daily users around the world. You may have taken them camping. Among its customers are international aid agencies and relief organizations, such as WaterAid and various governmental ministries of health.

"Chlorine is an affordable even for the poorest of the poor ($0.25 per month) and widely available," says Jeff Albert, vice-chair and co-founder of the Aquaya Institute, a non-profit research and consulting organization aimed at improving health in the developing world. "If I were a slum dweller in Dhaka or Addis Ababa," he adds, "I would dose my jerry can of well water with dilute hypochlorite solution."

Alas, despite its affordability and ubiquity, chlorine has its drawbacks. It does not remove sediment if the water is particularly turbid or murky. More important, chlorine doesn't remove giardia and a few other pathogens that are notoriously resistant to chlorine.

One of the oldest tools in the shed: ceramics

Since time immemorial, people have been heating clay to temperatures hovering around melting levels (called vitrification) in order to make "ceramic" vessels for food and water. Not until the mid-1800s, however, did we realize that clay heated just short of melting can become unusually fine-grained sieves. This makes a superb water filter, capable of removing both bacteria and protozoa.

Potters for Peace (PFP) has been working with organizations such as WaterAid to provide locally made ceramic pots. The PFP design was developed in 1981 by Dr. Fernando Mazariegos of the Central American Industrial Research Institute in Guatemala. It consists of clay in a flowerpot shape mixed with rice husks that are coated with colloidal silver, which removes bacteria and prevents bacterial growth in the filter. Based in Arizona, PFP has helped train and set up 50 ceramic filter factories in dozens of countries in Latin America and Africa. PFP made sure that its design is open source, meaning anyone or any organization can use it for free.

Equally important, these filters are often relatively affordable, even for poor families. A household can filter 20 liters of water a day at a cost of $0.034-0.14. The filter is built to last for three years.

While these filters are growing in popularity in lower-middle income countries, they are not as effective at removing viruses as some other options. And filters can break, requiring available spare parts. They also must be cleaned regularly.

This points to a sad reality to many ideas in the world of international development: Promising solutions often don't correspond with local needs, because benefactors failed at to address some basic, initial questions. Is the technology simple to use by people without much formal education? And is there a local supply chain of replacement parts, or alternatives, when things break or go wrong?

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